Preparation of beta-methyl-cyclopentadecanone



-muscon, is an important primary material in perfumery.

Patented Oct. 17, 1950 UNITED STATES PREPARATION OF BETA-METHYL-CYCIIO- 1 PENTADE CANDNE Max Stoll, Geneva, Switzerland, assignorr to Firmenich & Co., successenrs de la .Socit Anonyme M. Naef & Cie, Geneva, Switzerland, acorporationof Switzerland 1 6 Claims.

The present invention relates to a new process for preparing c methyl cyclo pentadecanone. This compound, which is identical with racemic It was hitherto prepared synthetically from cyclopenta-decanone (Helv. chim. acta 1'7, 1309 1934), from p-methylated dinitril of thapsic acid (A. 512, 162 .1934). or from ethylic w-brom-p-keto-t-methyl-hexadecanoate (B. 75,

materials that are very expensive or dimcult to obtain.

The process to which the present invention and byketonic splitting, according to the vfollowmg schema: I cmooorcnmoooom oH wHewoH Br('OHz)mBr 11 III 7 IV V some 0 CH(OH2).1oCH- C one; 03300 (CH1) 12CO on; o 0 R .OOR. I

or from (H) methyl'cycloheiianon'e (Formula v1),

9 which is oxidised in aacetylvaleric acid (Formula 1197 1942), 'all of these methods using primary VII) and then electrolysed in the presence of 4.0- acetylpelargonic acid (Formula VIII) obtained 'fromundecylenic acid, according to the following schema: I r v COCH:

relates is based, on the contrary, on the utilisation of a new and easily available primary material, viz. the 1.12-,diacety1dodecane (Formula I) I I CI-IaCO-(CHz) 12COCH The latter can, indeed, be prepared either from (i) sebacic acid ester (Formula II) by conversion OCHQ 5 or'by still other methods.

Conversion of the diacetyldodecane (Formula 1) into p-me'thyl-cyclo-pentadecanone (Formula XI) according to'the process of the invention is effected very simply by intramolecular condensa- 30 tion, yielding the compound of Formula IX, followed by dehydration, yielding the compound of Formula X, the latter being then hydrogenated, preferably in the presence of a catalyst. The whole operation proceeds according to the folinto decamethylene glycol (Formula III) in the 5 lowing schema:

COOH;

usual way (Helv. chim. acta 9, 265 1926), then into dibromodecane (Formula IV), followed by condensation with aceto-acetic acid ester so as to obtain the compound according to Formula V C-CHs (11911 l H-CO-CHa ring with 13 members C-CHa CH-CH$ 2 (CH2)12 012 CH2 COCH2 -COCH (3:0

IX X XI 1.12-diacetyldodecane should be.

In practice, however, the 15-membered ringproduct is chiefly obtained. This may be partly due to the fact that the 15-membered ring is formed more than four times as readily as its 13-membered rival. Of all. the homologous ketones having a musk odour--i. e., having 15, 16 or 17 members in their ring-only the 15-membered one offers such a marked difference in its facility of formation as compared with that of its homologue having two members less in its ring. The 1.12-diacetyldodecane thus possesses a constitution especially favourable to an intramolecular ring-closing on the methyl group.

To facilitate intramolecular condensation, it is strongly recommended to employ the 1.12-diacetyldodecane in a very dilute state. The less active the condensing agent is, the more diluted the The condensing agents to be taken into account are those known to be able to condense methyl-ketones in general and, in particular, magnesium-bromides of alkyl-anilines and hydrids of sodium (NaH). As organic solvents, ethers may be used, such as sulphuric ether and its homologues, ketals, aromatic and aliphatic hydrocarbons, alcohols, etc., either pure or mixed.

Intramolecular condensation followed by dehydration yields the dehydrated product'of condensation. By simple catalytic hydrogenation,

this product is quantitatively converted into 8-methyl-cyclo-pentadecanone.

Example 200 cc. of an ethereal solution of BrMgN(CI-I3) Gel-I containing 0.1 gramme-molecule of Mg and 0.11

gramrne-molecule of methylaniline are introduced into 20 litres of absolute ether. Then into the boiling solution, over a period of 5 hours, 17 grammes of 1.12-diacetyldodecane with a melting-point of 825 C. is added. After cooling, 500 cc. of 11% hydrochloric acid are added. By washing with acid and water, the methylaniline is eliminated. The ethereal solution is then dried and the solvent distilled. 20 grammes of oily residues are obtained. These are extracted with petroleum ether to obtain 14 grammes of oil smelling strongly of musk and also of rose. 5 grammes of product remain insoluble; they consist of polymeric substances and of a little diacetyldodecane. On distillation, the 14 grammes of oil separate into two almost equal fractions, the first of which distils between 4 -105 C. under 0.01 mm. of pressure and possesses the following physical constants:

By catalytic hydrogenation, this first fraction is integrally converted into fl-methyl-cyclo-pentadecanone, the semicarbazone of which melts at 138-140" C. The odour of this ketone is identical with that of muscon.

What I claim is:

1. A process for preparing c-methyl-cyclot pentadecanone which comprises cyclizing 1.12- diacetyldodecane by intramolecular condensation to form ,3 methyl B hydroxy cyclopentadecanone, dehydrating the p-methyl-p-hydroxycyclopentadecanone to ,B-methyl-cyclopentadmenone and then saturating by hydrogenation the c-rnethyl-cyclopentadecenone to B-methyl-cyclopentadecanone.

2. The process as defined in claim 1 in which the 1.12 diacetyldodecane is intramolecularly condensed in a highly dilute solution thereof.

3. The process as defined in claim 1 in which the 1.12 diacetyldodecane is intramolecularly condensed in a highly dilute solution thereof in an organic solvent.

4. A process as defined in claim 1 wherein the saturation is efiected by catalytic hydrogenation. 5. A process as defined in claim 1 in which the intrarnolecular condensation is efiected in the presence of a condensing agent.

6. A process as defined in claim 1 in which the intramolecular condensation is effected in the presence of B1'MgN(CH3)CsI-Is.

MAX STOLL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,965,829 Guinot July 10, 1934 2,275,752 Goldberg Mar. 10, 1942 2,387,587 Hunsdiecker Oct. 23, 1945 FOREIGN PATENTS Number Country Date 448,770 Great Britain Mar. 19, 1935 OTHER REFERENCES Gilman, Organic Chemistry, John Wiley 8: Sons, New York, 1938, vol. I, page 27.

Akeenova Chemical Abstracts, vol. 35, 6238- 6240 (1941). 

1. A PROCESS FOR PREPARING B-METHYL-CYCLOPENTADECANONE WHICH COMPRISES CYCLIZING 1.12DICETYLDANONE BY INTRAMOLECULAR CONDENSATION TO FORM B - METHYL - B - HYDROXY - CYCLOPENTADECANONE, DEHYDRATING THE B-METHYL-B-HYDROXYCYCLOPENTADECANONE TO B-METHYL-CYCLOPENTADECENONE AND THEN SATURATING BY HYDROGENATION THE B-METHYL-CYCLOPENTADECENONE TO B-METHYL-CYCLOPENTADECANONE. 